class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        unordered_map<int,int>map;
        for(int i=0;i<nums.size();i++){
            if(map.find(nums[i])!=map.end()){
                if(i-map[nums[i]]<=k){return true;}
                else{map[nums[i]]=i;}
            }
            else{map[nums[i]]=i;}
        }
        return false;
    }
};